There exists a variety of different stacked assemblies and structures in the context of electronics and electronic products. The motivation behind the integration of electronics and related products may be as diverse as the related use contexts. Relatively often size savings, weight savings, cost savings, or just efficient integration of components is sought for when the resulting solution ultimately exhibits a multilayer nature. In turn, the associated use scenarios may relate to product packages or food casings, visual design of device housings, wearable electronics, personal electronic devices, displays, detectors or sensors, vehicle interiors, antennae, labels, vehicle electronics, etc.
Electronics such as electronic components, ICs (integrated circuit), and conductors, may be generally provided onto a substrate element by a plurality of different techniques. For example, ready-made electronics such as various surface mount devices (SMD) may be mounted on a substrate surface that ultimately forms an inner or outer interface layer of a multilayer structure. Additionally, technologies falling under the term “printed electronics” may be applied to actually produce electronics directly and additively to the associated substrate. The term “printed” refers in this context to various printing techniques capable of producing electronics/electrical elements from the printed matter, including but not limited to screen printing, flexography, and inkjet printing, through a substantially additive printing process. The used substrates may be flexible and printed materials organic, which is however, not always the case.
Furthermore, the concept of injection molded structural electronics (IMSE) actually involves building functional devices and parts therefor in the form of a multilayer structure, which encapsulates electronic functionality as seamlessly as possible. Characteristic to IMSE is also that the electronics is commonly manufactured into a true three-dimensional (3D) (i.e., non-planar) form in accordance with the 3D models of the overall target product, part or generally design. To achieve desired 3D layout of electronics on a 3D substrate and in the associated end product, the electronics may be still provided on an initially planar substrate, such as a film, using two dimensional (2D) methods of electronics assembly, whereupon the substrate, already accommodating the electronics, may be formed into a desired 3D shape and subjected to overmolding, for example, by suitable plastic material that covers and embeds the underlying elements such as electronics, thus protecting and potentially hiding the elements from the environment.
In typical solutions, electrical circuits have been produced on a printed circuit board (PCB) or a on substrate film, after which they have been overmolded by plastic material. Known structures and methods have, however, some drawbacks, still depending on the associated use scenario. In order to produce an electronic assembly having one or more functionalities, typically rather complex electrical circuits for achieving these functionalities have to be produced on a substrate by printing and/or utilizing SMDs, and then be overmolded by plastic material. However, in the known solutions, the implementation of complex functionalities may face reliability risks and assembly yield issues arising from challenges in integrating very dense components and components with complex geometries. Furthermore, the electronic assembly may require, for example, the use of external control electronics which reduces degree of integration and makes the structures less attractive. Directly integrating dense components and components of complex geometry can be challenging and potentially very risky, as reliability will often be affected by molding pressure, for instance, and the assembly yields in different production phases can be very low. Subassemblies mounted or arranged on a PCB and covered with a plastic layer can suffer from mismatch in thermal expansion coefficients, be difficult to be overmolded due to their complex structure, and exhibit stresses in the structure which can tear the subassemblies off their electrical contacts. Challenges in thermal management may also generally cause issues such as overheating.
Many IMSE designs have e.g. individually connected all electrical signals out of the IMSE part or device, most often with a flexible circuit board tail (“flex”) bonded on an IMSE substrate with ACA (anisotropically conductive adhesive). A contemporary approach for IMSE connections is indeed to bring all the electrical connections out of the part or the device, and the part may easily have ten(s) or more signals to be brought out. Electrical connections between an IMSE structure and an external system may generally involve or implement power transfer (voltage/current supply) and/or data transfer (control and/or other data) in either direction. Furthermore, the system-facing connectivity has varied widely, for example, with only a selected bus type power convection arranged in some implementations and e.g. a network connection in others.
For example, “flex” type connection has proven challenging to implement in a reliable fashion in various use contexts while still maintaining a modicum of production automation as typically manual labor has been found necessary. On the other hand, many mechanically better (durable, secure, etc.) and more automation-friendly connectors have not been able to reach the desired connection density for bringing all electrical and power signals/connections out of the part. Therefore, there is still a need to develop solutions for interfacing various external systems with various IMSE parts or devices, the solutions being, besides robust and versatile, also more automation-friendly.